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authorPhil Carmody <ext-phil.2.carmody@nokia.com>2010-05-26 14:42:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-27 09:12:43 -0700
commit5407a56257b6ade44fd9bcac972c99845b7413cd (patch)
tree833a55856af25fe9be5e8a871d89f43677eac512 /mm/memcontrol.c
parentdf64f81bb1e01cbef967a96642dacf208acb7e72 (diff)
downloadvexpress-lsk-5407a56257b6ade44fd9bcac972c99845b7413cd.tar.gz
mm: remove unnecessary use of atomic
The bottom 4 hunks are atomically changing memory to which there are no aliases as it's freshly allocated, so there's no need to use atomic operations. The other hunks are just atomic_read and atomic_set, and do not involve any read-modify-write. The use of atomic_{read,set} doesn't prevent a read/write or write/write race, so if a race were possible (I'm not saying one is), then it would still be there even with atomic_set. See: http://digitalvampire.org/blog/index.php/2007/05/13/atomic-cargo-cults/ Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index be5f478351b..93b0239bc34 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -152,7 +152,7 @@ struct mem_cgroup_threshold {
/* For threshold */
struct mem_cgroup_threshold_ary {
/* An array index points to threshold just below usage. */
- atomic_t current_threshold;
+ int current_threshold;
/* Size of entries[] */
unsigned int size;
/* Array of thresholds */
@@ -3412,7 +3412,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
* If it's not true, a threshold was crossed after last
* call of __mem_cgroup_threshold().
*/
- i = atomic_read(&t->current_threshold);
+ i = t->current_threshold;
/*
* Iterate backward over array of thresholds starting from
@@ -3436,7 +3436,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
eventfd_signal(t->entries[i].eventfd, 1);
/* Update current_threshold */
- atomic_set(&t->current_threshold, i - 1);
+ t->current_threshold = i - 1;
unlock:
rcu_read_unlock();
}
@@ -3528,7 +3528,7 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
compare_thresholds, NULL);
/* Find current threshold */
- atomic_set(&thresholds_new->current_threshold, -1);
+ thresholds_new->current_threshold = -1;
for (i = 0; i < size; i++) {
if (thresholds_new->entries[i].threshold < usage) {
/*
@@ -3536,7 +3536,7 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
* until rcu_assign_pointer(), so it's safe to increment
* it here.
*/
- atomic_inc(&thresholds_new->current_threshold);
+ ++thresholds_new->current_threshold;
}
}
@@ -3607,7 +3607,7 @@ static int mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
thresholds_new->size = size;
/* Copy thresholds and find current threshold */
- atomic_set(&thresholds_new->current_threshold, -1);
+ thresholds_new->current_threshold = -1;
for (i = 0, j = 0; i < thresholds->size; i++) {
if (thresholds->entries[i].eventfd == eventfd)
continue;
@@ -3619,7 +3619,7 @@ static int mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
* until rcu_assign_pointer(), so it's safe to increment
* it here.
*/
- atomic_inc(&thresholds_new->current_threshold);
+ ++thresholds_new->current_threshold;
}
j++;
}